This invention relates to a fluid pressure controller suitable for use in a high-pressure, small-flow fluid pressure system such as a brake system for a vehicle, and more specifically to a device for controlling the rate of increase or decrease of the pressure (speed or in a strict sense, the rate of increase or decrease of the flow velocity) on the base of a value corresponding to the magnitude of an electric command.
The present applicant has proposed a variable flow control valve in Japanese Patent Application 1-272628. With this prior art variable flow control valve, a differential pressure corresponding to the magnitude of an electric command is produced between first and second fluid chambers formed at opposing ends of a spool through a variable-size orifice defined by a shoulder portion of the spool. The flow through the valve is controlled by a fixed-size orifice formed in a passage connecting both chambers so as to correspond to the differential pressure.
In order to use this valve for a variety of applications, two of such valves have to be prepared, one for pressure increase and the other for pressure reduction. This is inconvenient and uneconomical.